Reproductive Phenomena of the Amoeban Rhizopods. 337 



those previously described under the heads oT " gemmation" and 

 " viviparous parturition," a new brood of Amoeba appears to be 

 ushered into existence. For the present, therefore, I would 

 merely state that one series of young individuals seems to be 

 derived from the conversion of each free sarcoblast into a poly- 

 morphous body, devoid of cilia or flagelliforra organ, but pro- 

 vided from the first with a nucleus, a contractile vesicle, and a 

 rudimentary villous organ — that a second series, less frequent 

 than the last, seems to result from the similar conversion of each 

 encapsuled nucleus into a polymorphous body, in which, besides 

 the organs just enumerated, may frequently be seen two or three 

 spherical masses undistinguishable from the sarcoblasts ; whilst 

 a third and by far the most numerous brood appears to be de- 

 rived from each separate granule of the naked mulberry-like 

 nuclear masses which were described by me in the ' Annals ' for 

 May (p. 368) as being occasionally formed within the parent 

 Amoeba. The evidence of this last-mentioned mode of inci'ease 

 consists in the admixture of minute Amoebce with some of the 

 granules which are still quiescent, in their barely exceeding the 

 latter in size, and especially in the gradual transition observable 

 from the quiescent to the motile and polymorphous condition 

 of the granules. Of course it would be futile to attempt 

 an explanation of these processes in the present state of our 

 knowledge; for, although satisfied of the occurrence of these 

 varied methods of increase, I consider the questions they involve 

 as too important to be solved without much additional informa- 

 tion or on mere inferential reasoning. 



Lastly, I would mention another interesting fact which has 

 revealed itself within the past few days, but the details of which 

 must be supplied hereafter. I allude to the transition observed 

 to have taken place, in specimens of free Amoebce preserved alive 

 in shallow glass cells, from the naked to the testaceous condi- 

 tion — a form closely resembling, if not identical with, A. radiosa 

 having first assumed a state of comparative rest, as if about to 

 become encysted, and then gradually secreted the delicate hya- 

 line outer wall which ultimately presented the unmistakable 

 characters of the test of Arcella vulgaris. 



Kensington, October 20, 1863. 



Note. — I am permitted by Mr. Tomkins to state that, whilst 

 looking over the same material, he has distinctly seen the animal 

 of Arcella vulgaris evacuate its test, and move away in the garb 

 of a naked Amceban. This occuri'ence has often been regarded as 

 probable, but I am not aware that it had previously been actually 

 witnessed by an"^ trustworthy observer. 



